This invention relates to a biopsy needle for extracting tissue samples, the method for fabricating the same, and the apparatus for operating the needle.
The most widely used biopsy needles are a Silverman Needle and a Core Needle, which are generally called names in the field, The Silverman needle, as shown in FIG. 1, has an outer cannula 1 whose vertical hollow cross section is a circle, and a split needle 3 whose distal end is split to extract tissue samples. When using the needle of FIG. 1, the outer cannula 1 is forcibly inserted to an aimed internal organ or a tumor, and then the split needle 3 moves forward out of the cannula 1 into the organ. At that time, the split distal ends of the needle 3 become wide open due to elasticity of the needle and resistance of the tissue of the organ. When the cannula 1 reaches to an aimed organ, the needle 3 retracts and grips the tissue, as shown in FIG. 2. In this state, rotating the outer cannula 1 and the split needle 3 about its longitudinal axis once or twice separates the gripped sample from the tissue.
FIG. 3 shows a Core Needle having an outer needle 5 whose vertical hollow cross section is circle-shaped, and an inner needle 7 for gripping the tissue inside the outer needle 5. The inner needle 7 is a solid tubular body not to admit unnecessary tissue to enter the outer needle, and has a groove 7a about 4 or 5 mm distant from the distal end for acquiring sample.
When using the Core needle, the outer needle 5 advances into the aimed internal organ with the inner needle 7, which firstly moves forward into the tissue and the groove 7a of which accommodates samples of the aimed tissue, after that the outer needle 5 moves more into the tissue to remove the samples contained in the groove 7a from the tissue.
In case of the Silverman needle explained above, to extract enough samples, the outer cannula should be of a larger diameter, since the samples are acquired by the split needle inside the outer cannula. Also, it has been used only in soft organs, since the hardness of the split needle is not strong enough to penetrate into a hard tissue.
In case of Core needle, it can not extract enough samples either, since the samples are acquired by a groove of the inner needle. Thus, to get the enough samples, most users uses a big diameter Core needle or extracts samples several times. Also, since the groove is located about 4 to 5 mm away from the dismal end, it is difficult to acquire an aimed positioned sample and the inner needle should move forward more deeply than the position of the aimed tissue, which may hurt adjacent organs without intention.
Also, this kind of needle can not be mounted on an auto biopsy gun, since the gun generally shoots needles only to a fixed determined depth. Thus, the needle should be handled by hand, which needs more than 20 kgf in some cases.
That is to say, since the needles of the types explained above uses an outer needle for penetrating and an inner needle for acquiring samples, the size of acquired samples are small comparing thickness of the outer needle, thus the size of the outer needle needs to be larger for enough samples, or the operation should be done several times, both of which may wound organs in many points.
Also, both the needles cannot acquire liquid or gaseous phased samples. And since both Silverman and Core needles can be used in a somewhat deep organs, it is inconvenient to extract samples from cuticle or pathological tissues.
Other biopsy needles are disclosed in U.S. Pat. Nos. 5,251,641, 4,926,877, and 5,526,821, which are not being used in the field. The 877"" patent has the same problem as the above two needles in that the whole cross section area of the outer needle is not contributed to acquire samples.
It is therefore an overall object of present invention to provide a biopsy needle with a small size (diameter) which can enlarge the size of the acquired samples by the needle.
It is an another object of the invention to provide a method for fabricating the above needle.
It is still another object of the invention to provide an apparatus for operating the biopsy needle.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.
The invention discloses a needle which can be used to acquire samples without an inner needle, thus it can acquire relatively bigger sample than the needle assembly having an inner needle and an outer needle.
The needle of this invention is hollow tubular shaped, and the cross section of the hollow section taken vertically to the longitudinal direction is elliptical shaped.
The samples captured in the needle are extracted by twisting the needle, which is possible since the hollow section of the needle is not circle-shaped.
Separating the samples from the aimed tissue may be accomplished by a needle with a twisting rectangular or triangular or any polygonal shaped hollow section, but, it is preferable to make the hollow section of the needle elliptical regarding convenience of manufacturing, impact of twisting tissue, size of samples acquired.
Furthermore, the needle of the invention has an inwardly beveled distal end to acquire bigger size of the samples.
Though the needle is basically structured to have an elliptical hollow section and an inwardly beveled distal end, to improve the separation of samples a portion of the distal end of the needle is outwardly beveled, whereas the other portion is inwardly beveled.
Meanwhile, the method for manufacturing the biopsy needle of the invention has providing a hollow tube, drawing the hollow tube so that the hollow section of the tube becomes elliptical shaped, cutting the tube in a predetermined length, and machining an distal end of the tube to be inwardly beveled.
To improve penetrating, the method may further comprise machining the outer circumferential portion of the distal end of the tube to be outwardly beveled after machining the distal end to be inwardly beveled.
Alternatively, another method of the invention has a step of machining the distal end of the tube so that a portion of the distal end is outwardly beveled and that the other portion is inwardly beveled.
According to the invention, to make the inner hollow section of the needle elliptical, pressing the tube to make whole tube elliptical may be adapted instead of drawing the tube. This method is useful, when the diameter of the tube is so small that drawing the tube to have a hollow elliptical cross section is difficult.
This invention also discloses the apparatus for handling the biopsy needle, which has an acting part where the needle is mounted and the needle is translated and rotated, and a driving part for transmitting translation force and rotation force to the acting part. The apparatus further comprises a handling part for easy handling of the driving part. When the structure of the aimed tissue is hard and requires a big force, the acting part may be divided as a translation acting part and a rotating acting part.